not really oscillation...
I tested it with oscilloscope... it's ok...
well...it at least take 10 sec to be stable....
I think I'll get a delay circuit .... since I always forgot turn on my tube pre-amp first... @@

Quote:

Originally posted by ShiFtY You might have some sort of oscillation? Hmmm...

Are you using a solid state power amp?
If so this warm up instability is normal. You may want to try fitting a timer delay until your valves have reached their operating temp.
It sounds like your diong the right thing by delaying the turn on of your power amp.
Phil.